Use this in all the places where sleeping with the lock held is not
an issue.
The distinction will become significant once we finalize the exact
lock-type to use for this kind of case.
(sorele()/sotryfree()):
- This permits the caller to acquire the accept mutex before the socket
mutex, avoiding sofree() having to drop the socket mutex and re-order,
which could lead to races permitting more than one thread to enter
sofree() after a socket is ready to be free'd.
- This also covers clearing of the so_pcb weak socket reference from
the protocol to the socket, preventing races in clearing and
evaluation of the reference such that sofree() might be called more
than once on the same socket.
This appears to close a race I was able to easily trigger by repeatedly
opening and resetting TCP connections to a host, in which the
tcp_close() code called as a result of the RST raced with the close()
of the accepted socket in the user process resulting in simultaneous
attempts to de-allocate the same socket. The new locking increases
the overhead for operations that may potentially free the socket, so we
will want to revise the synchronization strategy here as we normalize
the reference counting model for sockets. The use of the accept mutex
in freeing of sockets that are not listen sockets is primarily
motivated by the potential need to remove the socket from the
incomplete connection queue on its parent (listen) socket, so cleaning
up the reference model here may allow us to substantially weaken the
synchronization requirements.
RELENG_5_3 candidate.
MFC after: 3 days
Reviewed by: dwhite
Discussed with: gnn, dwhite, green
Reported by: Marc UBM Bocklet <ubm at u-boot-man dot de>
Reported by: Vlad <marchenko at gmail dot com>
a more complete subsystem, and removes the knowlege of how things are
implemented from the drivers. Include locking around filter ops, so a
module like aio will know when not to be unloaded if there are outstanding
knotes using it's filter ops.
Currently, it uses the MTX_DUPOK even though it is not always safe to
aquire duplicate locks. Witness currently doesn't support the ability
to discover if a dup lock is ok (in some cases).
Reviewed by: green, rwatson (both earlier versions)
fcntl() operations, including:
F_DUPFD dup() alias
F_GETFD retrieve close-on-exec flag
F_SETFD set close-on-exec flag
F_GETFL retrieve file descriptor flags
For the remaining fcntl() operations, do acquire Giant, especially
where we call into fo_ioctl() as a result. We're not yet ready to
push Giant into fo_ioctl(). Once we do, this can all become quite a
bit prettier.
Giant conditional on debug.mpsafenet in the socket soo_stat() routine,
unconditionally in vn_statfile() for VFS, and otherwise don't acquire
Giant. Accept an unlocked read in kqueue_stat(), and cryptof_stat() is
a no-op. Don't acquire Giant in fstat() system call.
Note: in fdescfs, fo_stat() is called while holding Giant due to the VFS
stack sitting on top, and therefore there will still be Giant recursion
in this case.
individual file object implementations can optionally acquire Giant if
they require it:
- soo_close(): depends on debug.mpsafenet
- pipe_close(): Giant not acquired
- kqueue_close(): Giant required
- vn_close(): Giant required
- cryptof_close(): Giant required (conservative)
Notes:
Giant is still acquired in close() even when closing MPSAFE objects
due to kqueue requiring Giant in the calling closef() code.
Microbenchmarks indicate that this removal of Giant cuts 3%-3% off
of pipe create/destroy pairs from user space with SMP compiled into
the kernel.
The cryptodev and opencrypto code appears MPSAFE, but I'm unable to
test it extensively and so have left Giant over fo_close(). It can
probably be removed given some testing and review.
check to ensure that the caller is not prison root.
The intention is to fix file descriptor creation so that
prison root can not use the last remaining file descriptors.
This privilege should be reserved for non-jailed root users.
Approved by: bmilekic (mentor)
reference count:
- Assert SOCK_LOCK(so) macros that directly manipulate so_count:
soref(), sorele().
- Assert SOCK_LOCK(so) in macros/functions that rely on the state of
so_count: sofree(), sotryfree().
- Acquire SOCK_LOCK(so) before calling these functions or macros in
various contexts in the stack, both at the socket and protocol
layers.
- In some cases, perform soisdisconnected() before sotryfree(), as
this could result in frobbing of a non-present socket if
sotryfree() actually frees the socket.
- Note that sofree()/sotryfree() will release the socket lock even if
they don't free the socket.
Submitted by: sam
Sponsored by: FreeBSD Foundation
Obtained from: BSD/OS
descriptors out of fdrop_locked() and into vn_closefile(). This
removes all knowledge of vnodes from fdrop_locked(), since the lock
behavior was specific to vnodes. This also removes the specific
requirement for Giant in fdrop_locked(), it's now only required by
code that it calls into.
Add GIANT_REQUIRED to vn_closefile() since VFS requires Giant.
the syscall arguments and does the suser() permission check, and
kern_mlock(), which does the resource limit checking and calls
vm_map_wire(). Split munlock() in a similar way.
Enable the RLIMIT_MEMLOCK checking code in kern_mlock().
Replace calls to vslock() and vsunlock() in the sysctl code with
calls to kern_mlock() and kern_munlock() so that the sysctl code
will obey the wired memory limits.
Nuke the vslock() and vsunlock() implementations, which are no
longer used.
Add a member to struct sysctl_req to track the amount of memory
that is wired to handle the request.
Modify sysctl_wire_old_buffer() to return an error if its call to
kern_mlock() fails. Only wire the minimum of the length specified
in the sysctl request and the length specified in its argument list.
It is recommended that sysctl handlers that use sysctl_wire_old_buffer()
should specify reasonable estimates for the amount of data they
want to return so that only the minimum amount of memory is wired
no matter what length has been specified by the request.
Modify the callers of sysctl_wire_old_buffer() to look for the
error return.
Modify sysctl_old_user to obey the wired buffer length and clean up
its implementation.
Reviewed by: bms
Introduce d_version field in struct cdevsw, this must always be
initialized to D_VERSION.
Flip sense of D_NOGIANT flag to D_NEEDGIANT, this involves removing
four D_NOGIANT flags and adding 145 D_NEEDGIANT flags.
- struct plimit includes a mutex to protect a reference count. The plimit
structure is treated similarly to struct ucred in that is is always copy
on write, so having a reference to a structure is sufficient to read from
it without needing a further lock.
- The proc lock protects the p_limit pointer and must be held while reading
limits from a process to keep the limit structure from changing out from
under you while reading from it.
- Various global limits that are ints are not protected by a lock since
int writes are atomic on all the archs we support and thus a lock
wouldn't buy us anything.
- All accesses to individual resource limits from a process are abstracted
behind a simple lim_rlimit(), lim_max(), and lim_cur() API that return
either an rlimit, or the current or max individual limit of the specified
resource from a process.
- dosetrlimit() was renamed to kern_setrlimit() to match existing style of
other similar syscall helper functions.
- The alpha OSF/1 compat layer no longer calls getrlimit() and setrlimit()
(it didn't used the stackgap when it should have) but uses lim_rlimit()
and kern_setrlimit() instead.
- The svr4 compat no longer uses the stackgap for resource limits calls,
but uses lim_rlimit() and kern_setrlimit() instead.
- The ibcs2 compat no longer uses the stackgap for resource limits. It
also no longer uses the stackgap for accessing sysctl's for the
ibcs2_sysconf() syscall but uses kernel_sysctl() instead. As a result,
ibcs2_sysconf() no longer needs Giant.
- The p_rlimit macro no longer exists.
Submitted by: mtm (mostly, I only did a few cleanups and catchups)
Tested on: i386
Compiled on: alpha, amd64
in OpenBSD by Niels Provos. The patch introduces a bitmap of allocated
file descriptors which is used to locate available descriptors when a new
one is needed. It also moves the task of growing the file descriptor table
out of fdalloc(), reducing complexity in both fdalloc() and do_dup().
Debts of gratitude are owed to tjr@ (who provided the original patch on
which this work is based), grog@ (for the gdb(4) man page) and rwatson@
(for assistance with pxeboot(8)).
with one of std{in,out,err} open. This helps with the file descriptor
leaks reported on -current. This should probably be merged into 5.2.
Reviewed by: ru
Tested by: Bjoern A. Zeeb <bzeeb-lists@lists.zabbadoz.net>
table, acquiring the necessary locks as it works. It usually returns
two references to the new descriptor: one in the descriptor table
and one via a pointer argument.
As falloc releases the FILEDESC lock before returning, there is a
potential for a process to close the reference in the file descriptor
table before falloc's caller gets to use the file. I don't think this
can happen in practice at the moment, because Giant indirectly protects
closes.
To stop the file being completly closed in this situation, this change
makes falloc set the refcount to two when both references are returned.
This makes life easier for several of falloc's callers, because the
first thing they previously did was grab an extra reference on the
file.
Reviewed by: iedowse
Idea run past: jhb
fd_cmask field in the file descriptor structure for the first process
indirectly from CMASK, and when an fd structure is initialized before
being filled in, and instead just use CMASK. This appears to be an
artifact left over from the initial integration of quotas into BSD.
Suggested by: peter
malloc and mbuf allocation all not requiring Giant.
1) ostat, fstat and nfstat don't need Giant until they call fo_stat.
2) accept can copyin the address length without grabbing Giant.
3) sendit doesn't need Giant, so don't bother grabbing it until kern_sendit.
4) move Giant grabbing from each indivitual recv* syscall to recvit.
kern.file sysctl, don't return information about processes that
fail p_cansee(td, p). This prevents sockstat and related
programs from seeing file descriptors owned by processes not
in the same jail as the thread, as well as having implications
for MAC, etc.
This is a partial solution: it permits an information leak about
the number of descriptors in the sizing calculation (but this is
not new information, you can also get it from kern.openfiles),
and doesn't attempt to mask file descriptors based on the
properties of the descriptor, only the process referencing it.
However, it provides most of what you want under most
circumstances, without complicating the locking.
PR: 54211
Based on a patch submitted by: Pawel Jakub Dawidek <nick@garage.freebsd.pl>
multiple mutex pools with different options and sizes. Mutex pools can
be created with either the default sleep mutexes or with spin mutexes.
A dynamically created mutex pool can now be destroyed if it is no longer
needed.
Create two pools by default, one that matches the existing pool that
uses the MTX_NOWITNESS option that should be used for building higher
level locks, and a new pool with witness checking enabled.
Modify the users of the existing mutex pool to use the appropriate pool
in the new implementation.
Reviewed by: jhb
Several of the subtypes have an associated vnode which is used for
stuff like the f*() functions.
By giving the vnode a speparate field, a number of checks for the specific
subtype can be replaced simply with a check for f_vnode != NULL, and
we can later free f_data up to subtype specific use.
At this point in time, f_data still points to the vnode, so any code I
might have overlooked will still work.
we can deadlock because of lock order reversals. This was not
caught because Witness ignores pool mutexes right now.
Diagnosis and help: truckman
Noticed by: pho
systems to fail more gracefully when a file descriptor exhaustion situation
occurs.
Original patch by: David G. Andersen <dga@lcs.mit.edu>
PR: 45353
MFC after: 1 week
branches:
Initialize struct cdevsw using C99 sparse initializtion and remove
all initializations to default values.
This patch is automatically generated and has been tested by compiling
LINT with all the fields in struct cdevsw in reverse order on alpha,
sparc64 and i386.
Approved by: re(scottl)
- Mark the process leader as having an advisory lock
- Check if process leader is marked as having advisory lock when
closing file
- Check that file is still open after lock has been obtained
- Don't allow file descriptor table sharing between processes
with different leaders
PR: 10265
Reviewed by: alfred
barrier between free'ing filedesc structures. Basically if you want to
access another process's filedesc, you want to hold this mutex over the
entire operation.
The locking here needs to be revisited, but this ought to get rid of the
LOR messages that people are complaining about for now. I imagine either
I or someone else interested with smp will eventually clear this up.
was used to control code which were conditional on DEVFS' precense
since this avoided the need for large-scale source pollution with
#include "opt_geom.h"
Now that we approach making DEVFS standard, replace these tests
with an #ifdef to facilitate mechanical removal once DEVFS becomes
non-optional.
No functional change by this commit.
pointer types, and remove a huge number of casts from code using it.
Change struct xfile xf_data to xun_data (ABI is still compatible).
If we need to add a #define for f_data and xf_data we can, but I don't
think it will be necessary. There are no operational changes in this
commit.
The leak in lseek was introduced in vfs_syscalls.c revision 1.218.
The leak in do_dup was introduced in kern_descrip.c revision 1.158.
Submitted by: iedowse
take pointers to filedesc structures instead of threads. This makes
it more clear that they do not do any voodoo with the thread/proc
or anything other than the filedesc passed in or returned.
Remove some XXX KSE's as this resolves the issue.
These call uma_large_malloc() and uma_large_free() which require Giant.
Fixes panic when descriptor table is larger than KMEM_ZMAX bytes
noticed by kkenn.
Reviewed by: jhb
instead of panicing. Also, perform some of the simpler sanity checks on
the fds before acquiring the filedesc lock.
Approved by: re
Reported by: Dan Nelson <dan@emsphone.com> and others
to conform to 1003.1-2001. Make it possible for applications to actually
tell whether or not asynchronous I/O is supported.
Since FreeBSD's aio implementation works on all descriptor types, don't
call down into file or vnode ops when [f]pathconf() is asked about
_PC_ASYNC_IO; this avoids the need for every file and vnode op to know about
it.
dereference the struct sigio pointer without any locking. Change
fgetown() to take a reference to the pointer instead of a copy of the
pointer and call SIGIO_LOCK() before copying the pointer and
dereferencing it.
Reviewed by: rwatson
v_tag is now const char * and should only be used for debugging.
Additionally:
1. All users of VT_NTS now check vfsconf->vf_type VFCF_NETWORK
2. The user of VT_PROCFS now checks for the new flag VV_PROCDEP, which
is propagated by pseudofs to all child vnodes if the fs sets PFS_PROCDEP.
Suggested by: phk
Reviewed by: bde, rwatson (earlier version)
it can do it w/o needing to hold the filelist_lock sx lock.
- fdalloc() doesn't need Giant to call free() anymore. It also doesn't
need to drop and reacquire the filedesc lock around free() now as a
result.
- Try to make the code that copies fd tables when extending the fd table in
fdalloc() a bit more readable by performing assignments in separate
statements. This is still a bit ugly though.
- Use max() instead of an if statement so to figure out the starting point
in the search-for-a-free-fd loop in fdalloc() so it reads better next to
the min() in the previous line.
- Don't grow nfiles in steps up to the size needed if we dup2() to some
really large number. Go ahead and double 'nfiles' in a loop prior
to doing the malloc().
- malloc() doesn't need Giant now.
- Use malloc() and free() instead of MALLOC() and FREE() in fdalloc().
- Check to see if the size we are going to grow to is too big, not if the
current size of the fd table is too big in the loop in fdalloc(). This
means if we are out of space or if dup2() requests too high of a fd,
then we will return an error before we go off and try to allocate some
huge table and copy the existing table into it.
- Move all of the logic for dup'ing a file descriptor into do_dup() instead
of putting some of it in do_dup() and duplicating other parts in four
different places. This makes dup(), dup2(), and fcntl(F_DUPFD) basically
wrappers of do_dup now. fcntl() still has an extra check since it uses
a different error return value in one case then the other functions.
- Add a KASSERT() for an assertion that may not always be true where the
fdcheckstd() function assumes that falloc() returns the fd requested and
not some other fd. I think that the assertion is always true because we
are always single-threaded when we get to this point, but if one was
using rfork() and another process sharing the fd table were playing with
the fd table, there might could be a problem.
- To handle the problem of a file descriptor we are dup()'ing being closed
out from under us in dup() in general, do_dup() now obtains a reference
on the file in question before calling fdalloc(). If after the call to
fdalloc() the file for the fd we are dup'ing is a different file, then
we drop our reference on the original file and return EBADF. This
race was only handled in the dup2() case before and would just retry
the operation. The error return allows the user to know they are being
stupid since they have a locking bug in their app instead of dup'ing
some other descriptor and returning it to them.
Tested on: i386, alpha, sparc64
